E-paper (electronic paper) is now more and more popular because of its lower energy consumption, paper-like soft display behavior and thus of substituting for paper. Due to its excellent image keeping characteristic, E-paper is especially suitable for static display products for text reading and the like.
A fundamental principle of the E-paper is that charged particles in an electrophoretic fluid may reflect ambient light and then display an image which is received by human eyes. In an image converting phase, positions of the charged particles in the electrophoretic fluid may be controlled by a power-up voltage across the electrophoretic fluid and duration of the power-up voltage. Therefore the strength of the reflected light is controlled to achieve a gray-scale display. In an image keeping phase, the positions of the charged particles in the electrophoretic fluids are kept for the equal potential over both ends of the electrophoretic fluid, thus a static image display with lower energy consumption can be achieved.
When a user is reading, E-paper consumes electrical energy only if the user refreshes a page, otherwise, E-paper can display continuously even if its power is turned off. Therefore, E-paper displays with lower power consumption. Moreover, E-paper has a characteristic of high reflection in which the E-paper displays without backlight and achieves a black-and-white display or a color display by reflection of ambient light. Unlike a currently used transparent display LCD (Liquid Crystal Display), the E-paper, which displays by means of reflection, has good display properties even when used in a very bright environment.
E-paper displays include color displays and black-and-white displays. FIG. 1 is a schematic cross-sectional diagram of an E-paper for black-and-white display in the related art. Referring to FIG. 1, the E-paper for black-and-white display includes a TFT (Thin-Film Transistor) array substrate 10 and a display substrate 20. The TFT array substrate 10 includes a glass substrate 11 and storage capacitors formed on the glass substrate 11, where each of the storage capacitors consists of a common electrode 12, a capacitor medium layer 13 and a pixel electrode 14. Material of the common electrode 12 is an opaque metal and material of the pixel electrode 14 is transparent ITO (Indium Tin Oxides). The display substrate 20 includes an E-paper film 21 and a PET (Polyethylene terephthalate) substrate 23 combined with the E-paper film 21, where the PET substrate 23 is provided thereon with a transparent electrode 22, and PET, namely Polyethylene terephthalate, is a main type of thermoplastic polyester. In the related art, it is common to employ the microcapsule paper film in which there are negatively charged black particles and positive charged white particles. A main principle of the black-and-white display is that: a reference voltage is applied to the transparent electrode 22, corresponding pixel voltages are applied to respective ones of the pixel electrodes 14 via a data line, and the potential differences of pixels, which are the potential differences between the pixel electrodes 14 and the transparent electrode 22, are controlled to implement the control to the moving direction of the negatively charged black particles and the positively charged white particles in the pixel area. Since the white particles reflect light and the black particles absorb light, when the positively charged white particles gather at the side close to the PET substrate 23, white is displayed at the place where the white particles gather; and when the negatively charged black particles gather to the side close to the PET substrate 23, black is displayed at the place where the black particles gather.
To obtain an E-paper for color display, a color filter (CF) plate is added to the E-paper for black-and-white display. Currently, a color E-paper display panel mainly contains three parts: a TFT array substrate, a CF plate and a display substrate consisting of a PET substrate and an E-paper film. FIG. 2 is a schematic cross-sectional diagram of a color E-paper in the related art. A display substrate 20 is located on a TFT array substrate 10 and a CF plate 30 is located on the display substrate 20. The principle of the color E-paper is that: after passing through the CF plate 30, the light reflected by the white particles present a color image.
However, for the color E-paper in the related art, the CF plate 30 is needed for the purpose of color display. The presence of the CF plate leads to an increase in thickness of the E-paper, and only the color display rather than both the color display and the black and white display can be achieved.